How we change what others think, feel, believe and do
The Sound Duration Effect
Set prices using numbers that are shorter, with fewer syllables. For example, ten has one syllable while eleven has three (which is why ten can seem surprisingly smaller than eleven).
When you read out prices, use a method that reduces the number of syllables, for example reading '$1435' as 'one four three five' rather than 'one thousand, four hundred and thirty five'. You can even use approximations for large numbers, such as 'Just over fourteen hundred'.
Sound duration is also affected by the speed at which you speak, so reading a price quickly may make it seem smaller than if you say it quickly.
You can of course do the reverse if you want something to sound expensive, reading it out slowly.
A car salesperson quickly reads out the digits of a car price, also using additional abbreviation, saying 'fourteen two' rather than 'fourteen thousand, two hundred'.
A school selling after-time classes, prices them at $10 (one syllable) rather than $11 (three syllables) or using such as '$9.99' (four syllables).
When we are determining how big something is, we may use short-cut heuristics rather than thinking too closely about the actual number. One way we do this is by length, such as in the price length effect. The aural equivalent of visual length is simply a count of the syllables. Something that sounds longer suggests that it is somehow bigger. This is also why saying a price quickly can make it seem less.
The 99 effect can have a reverse effect here, as it adds to duration and can make a price seem more. This is particularly true if it is used in larger numbers, such as '$1435.99', so such cases it may be better to not use it.
Other factors that can indicate size may also have an aural effect. For example if you speak more loudly or more clearly, the price may seem more. The effect can be further modified by the emphasis put on words (for example emphasizing 'thousand' can make a price seem bigger).
Coulter, K.S., Choi, P. and Monroe, K.B. (2012). Comma N' cents in pricing: The effects of auditory representation encoding on price magnitude perceptions, Journal of Consumer Psychology, 22, 3, 395-407